netdev - [PATCH net 4/4] net: Comment copy_from_sockptr() explaining its behaviour

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Message-Id: <20241115-sockptr-copy-fixes-v1-4-d183c87fcbd5@rbox.co>
Date: Fri, 15 Nov 2024 00:27:27 +0100
From: Michal Luczaj <mhal@...x.co>
To: Marcel Holtmann <marcel@...tmann.org>, 
 Johan Hedberg <johan.hedberg@...il.com>, 
 Luiz Augusto von Dentz <luiz.dentz@...il.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
 David Howells <dhowells@...hat.com>, Marc Dionne <marc.dionne@...istor.com>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>, 
 linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org, 
 linux-afs@...ts.infradead.org, Jakub Kicinski <kuba@...nel.org>, 
 Michal Luczaj <mhal@...x.co>
Subject: [PATCH net 4/4] net: Comment copy_from_sockptr() explaining its
 behaviour

copy_from_sockptr() has a history of misuse. Add a comment explaining that
the function follows API of copy_from_user(), i.e. returns 0 for success,
or number of bytes not copied on error.

Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 include/linux/sockptr.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/sockptr.h b/include/linux/sockptr.h
index 195debe2b1dbc5abf768aa806eb6c73b99421e27..3e6c8e9d67aef66e8ac5a4e474c278ac08244163 100644
--- a/include/linux/sockptr.h
+++ b/include/linux/sockptr.h
@@ -53,6 +53,8 @@ static inline int copy_from_sockptr_offset(void *dst, sockptr_t src,
 /* Deprecated.
  * This is unsafe, unless caller checked user provided optlen.
  * Prefer copy_safe_from_sockptr() instead.
+ *
+ * Returns 0 for success, or number of bytes not copied on error.
  */
 static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
 {

-- 
2.46.2